Technical Field
The technique of the present disclosure relates to a fuel tank system and a method for sensing perforation.
Related Art
A fuel tank system, in which a valve member (a diaphragm valve) is provided at a vent pipe that communicates a fuel tank with a canister, is known (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2013-144942). In this fuel tank system, at usual times, the valve member is closed and the fuel tank is sealed. On the other hand, at the time of carrying out sensing as to whether or not perforation has arisen at the fuel tank (hereinafter simply called “perforation sensing”), by applying negative pressure to a back pressure chamber of the valve member and opening the valve member, negative pressure of a pump for diagnosis is introduced into the fuel tank. Concretely, negative pressure from the pump for diagnosis is applied to the back pressure chamber by providing a canister-side bypass path that communicates the vent pipe, that is at the canister side, and the back pressure chamber of the valve member.
In such a fuel tank system, some time is required from the application of negative pressure by the pump for diagnosis until the valve member opens, and this time affects the time required for perforation sensing.